Modifies standalone G-API cmake for testing it properly

modules/gapi/CMakeLists.txt

 # FIXME: Rework standalone build in more generic maner
 # (Restructure directories, add common pass, etc)
 if (NOT DEFINED OPENCV_INITIAL_PASS)
+    cmake_minimum_required(VERSION 3.3)
     include("cmake/standalone.cmake")
     return()
 endif()

modules/gapi/cmake/standalone.cmake

+if("${CMAKE_BUILD_TYPE}" STREQUAL "")
+  set(CMAKE_BUILD_TYPE "Release")
+endif()
+
 if (NOT TARGET ade )
   find_package(ade 0.1.0 REQUIRED)
 endif()
@@ -23,7 +27,7 @@ target_include_directories(${FLUID_TARGET}
   PUBLIC          $<BUILD_INTERFACE:${FLUID_ROOT}/include>
   PRIVATE         ${FLUID_ROOT}/src)
 
-target_compile_definitions(${FLUID_TARGET} PUBLIC -DGAPI_STANDALONE
+target_compile_definitions(${FLUID_TARGET} PUBLIC GAPI_STANDALONE
 # This preprocessor definition resolves symbol clash when
 # standalone fluid meets gapi ocv module in one application
                                            PUBLIC cv=fluidcv)
@@ -31,4 +35,9 @@ target_compile_definitions(${FLUID_TARGET} PUBLIC -DGAPI_STANDALONE
 set_target_properties(${FLUID_TARGET} PROPERTIES POSITION_INDEPENDENT_CODE True)
 set_property(TARGET ${FLUID_TARGET} PROPERTY CXX_STANDARD 11)
 
+if(MSVC)
+  target_compile_options(${FLUID_TARGET} PUBLIC "/wd4251")
+  target_compile_definitions(${FLUID_TARGET} PRIVATE _CRT_SECURE_NO_DEPRECATE)
+endif()
+
 target_link_libraries(${FLUID_TARGET} PRIVATE ade)